How To Decide What To Keep In A Faraday Cage For EMP

Faraday Cage for Just-in-case?

There are a lot of posts here on the blog about the topic of EMP (electromagnetic pulse). There have been a number of posts about the Faraday cage too (electronic device protection from EMP). We have also discussed ideas about what to keep in a Faraday cage, for just-in-case. It’s time to revisit…

[ EMP Category ]

Just the other day I was looking at one of my ordinary galvanized 30-gallon trash pails. FYI they can be repurposed as a makeshift Faraday cage for “some” protection (about 20 – 40 dB if done correctly). For whatever reason (maybe today’s crazy times?) I started thinking about EMP and the whole subject of what’s worth protecting in a Faraday cage, and Why.

Several issues make it somewhat difficult to consider.

  1. The cost of storing these electronic “things / devices” because they would be separately purchased backups which would be out of service during normal times.

2. The real world effectiveness of your Faraday cage coupled with the many theoretical EMP factors which would affect and vary the resultant outcome (what survives and what doesn’t).

3. One’s personal risk-tolerance threshold for doing it in the first place. In other words, the likelihood of the EMP event ever actually really happening versus tying up money in the project.

Which Backups Might Be Important?

In a perfect world you would love to store Faraday backups of all electronic devices for all your “things”. One of everything, right? Well, that would probably be ridiculous unless you’re filthy rich.

With that said, the reality of life after an EMP event will be drastically severe. Think it through. This will affect your decisions about what you might decide to protect (attempt to protect) from EMP. Or what not to bother with…

[ Read: If The Lights Went Out ]

We don’t know exactly how much, or to what extent, an EMP (or several simultaneous) will fry electronic devices within its sphere of a short (nanoseconds) intense zap of 50,000 volts /sq.meter destruction. Some things will survive it. Some won’t. There are variables / factors that will determine the extent (beyond the scope of this article).

I only say that because the world has not experienced a purpose-designed nuclear EMP high altitude detonation (except by accident many decades ago during nuke tests over the Pacific). And that was way before the days of today’s electronic infrastructure. We just don’t know with absolute certainty.

How To Decide What Goes In The Faraday Cage

So with all of that said, here’s what I was thinking about as I looked at that 30-gallon metal trash pail pictured above.

Keep the decision process simple and focused. Consider the electronic backups that would be THE MOST IMPORTANT FOR YOUR SURVIVAL, given your own personal situation and circumstances.

Presume that the grid will be down. This itself will create the nightmare.

What will you need to survive? Same as it always was… WATER, SHELTER, FOOD, SECURITY.

Of those categories, what electronic devices might serve you if they were protected in a Faraday cage. That’s what you would need to think about.

I reiterate, this will depend on your own personal situation. I will throw out a few thoughts as though it were my situation…

Water – Shelter – Food – Security

Related electronic device spares for my well water setup. Water! Though I could hoof it down to the natural spring every day – but that would get old real quick…

The well system (and other household systems) will not function without maintaining the operation of my off-grid solar energy system. Therefore the decisions about spares in this regard (I’m not going to list them all). Rather, just being general.

Shelter category considerations for me are simply the ability to heat my home in the winter, given my seasonally frigid location. Wood stove? No electrics required…

Food with regards to EMP falls into the cooking category. Methods thereof. My propane stove will operate without electricity (except the oven). Plus I have many additional methods to cook without electricity.

Special Emphasis On Security

Security. That’s an important one for sure. This is where Faraday may come in real handy.

  • AM/FM/Shortwave Battery Operated Radio and/or Ham radio (they work on 12-volt battery) for gathering “potential” information out there.
  • GMRS/FRS 2-Way Radios or Baofeng handhelds or similar for security comms. Consider extras to establish neighborhood security if that fits your AO personnel.
  • Battery Charger for Consumer type Batteries to keep those radios working. If you don’t have functioning off-grid electrics, then you’ll need solar panels to power your charger(s).
  • Solar panel (fold-able to fit in Faraday?) for power to Charger and other small load devices.
  • LED flashlights & headlamps
  • Old laptop that you might have replaced before. Maybe you keep important info on it for reference?
  • USB thumb drive(s) with any important files & info
  • Night Vision Device, if you have one. Though an expensive investment, it is a massive force multiplier. Protect it!

These are just a few thoughts. There certainly are more. However when it comes down to it, it may be easy to get carried away with thoughts of what to protect. The point I’m trying to make is “if” something like this were to happen, you might not need everything and “the kitchen sink” in that Faraday cage. Why? Because we would be in so much trouble – your biggest concern will probably be Security and just having enough food and water to survive! I won’t even bring up the notion of all those nuclear power plants out there!

[ Read: 5 Nanoseconds To Lights Out ]



  1. Ken,
    Do you use aluminum HVAC duct tape to seal the lid to the trash can?

    1. Romeo Charlie, never thought of HVAC aluminum tape, did use copper tape.

      1. Grey,
        I’m not an electrician nor a metallurgist but I’m guessing either copper or aluminum will work.

        1. OH,
          Yup. And you’ll probably have to repeat yourself a few more times. Asked some of my High Voltage researchers about this years ago, got the same answer. People can find the 2008 EMP report online,and the updates too. Few will take the time to seek it out and read it for themselves. Tea and chocolate Ol’ Son.

        2. I bow to your education, knowledge and experience. Confirms everything I’ve read & researched over the past 5+ yrs. Sincerely Thank You X 5.

    2. I dont think aluminum is properly conductive,
      steel or copper, this just from stuff i have read about EMF and electronic radiation,
      there is a lot of good info on this from a site called less emf
      they sell all sorts of woven products specifically made for shielding, i have bought fabrics from them for use in lining wallets and electronics cases, stuff really works

      1. Not saying EMP and EMF are the same thing, just that they are similar in properties and how they can be blocked, emf if much more damaging to people and their neuro biological while the pulse from an emp is more damaging to electrical and electronics, just know there is some overlap in shielding tech.

  2. So solar panels would get fried in an EMP? Or would it be the connections to send the power to batteries (and the batteries, maybe?) that get fried? We have a 3’x5′ solar panel to charge a battery for DH’s CPAP. We have an extra CPAP in the Faraday cage. Do I need to construct something for the solar panel?

    1. About Solar Panels some of the more “Modern” ones have micro-inverters built in. They provide 120 volt AC power. Those will be trashed by EMP. As they are built in I doubt that panel can be easily rebuilt to remove that burnt out micro-inverter and become a DC solar panel.

  3. What about those blood/sugar monitors for diabetes, and a O2/pulse monitor. Most people have spares of them already. I also have an electronic blood pressure reader (about $40). Now I don’t need these things for life or death at this time, but many people do.

    On another note, is it possible to tap into the light on a snow thrower to charge a 12v battery?
    I would hate to play around with my good one and mess up something!

    Does anyone know if the those inexpensive solar yard lights would survive an EMP?

    1. Nobody known for sure.
      I expect the closer your location to the actual blast the worse case scenario.
      There’s been much testing, many unshielded electronic items just needed to be turned off and on, they worked fine.
      Others they were damaged permanently.
      Some newer cars survived fine, some had electronic damage.. others were dead.

      In the end, luck of the draw and likely your location plus potentially shielded items.

      Anyone who claims they know beyond doubt, does not.

    2. from what I have seen and read… As long as the device doesn’t have a battery attached and there isn’t an electrical current in the device, it should be ok.

  4. Interesting article. The one thing I never see anyone store in their faraday cage is a digital multimeter. It is the ONE tool that will allow you to troubleshoot and possibly repair your other electronic/electrical items.

  5. I am not trying to find ways to keep electronics safe or make my own electricity. I am working on getting ready to live without electricity. I’m learning blacksmithing, gathering hand tools of all kinds, and I want to build a fire pit with an adjustable rack to do my canning on an open fire.

    1. car guy,
      Eventually we all may be there with ya. Many items are labor savers. Having a chainsaw, for example, would be a huge labor saver when compared to hand-saws and axes. Investing for a few priority items is not a bad idea. It’s always a trade off. I hope having a few items in faraday will allow for other things, security for example. Good luck to you sir.

      1. Yep. Also if you’re one of the few people in your area with vision devices that are still functioning after an EMP, you’ll have a huge advantage. I would expect that even LE’s and the National Guards equipment to be toast. As a former guardsman, I know that the equipment in our armory wasn’t protected against EMP while in storage.

    2. For several years I taught crosscut saw as well as chainsaw courses for the USFS. Over the years I have collected a few 2 man felling and bucking saws (various tooth styles) as well as several one man perforated lance tooth saws.

      We used them in Wilderness Ares where chainsaws were not allowed and if you know how to read binds and use wedges they are easy to use. I can file and sharpen them myself, they are quiet (won’t draw attention) and though I have several chainsaws the crosscut saws will be my go to when the SHTF.

      Never seen a crosscut saw not start but I’ve seen them run out of gas. 😀

  6. Ken, keeping a wood stove fed in the “seasonly frigid” location is going to be a full time job without chainsaws…I hope Mrs.J and Sampson are good with a splitting maul! I know my HH6 does not like to be cold…

  7. Heck, I don’t remember…I should have made a list and labeled.
    20 gal.
    There is an am/fm/sw solar-battery-handcrank radio.
    Batteries of all sizes.
    One CB unit.
    Two 12v inverters
    Solar panel is separately protected.
    Lid and seam taped with aluminum duct tape. And lined with cardboard.

    I need to get another can for an additional CB, set of 18v cordless batteries and its 12v charger.

    Sticking in some solar yard lights is a good idea.

    1. Truthfully, who the hell cares.
      Isn’t electricity and the new norm gadgets, a luxury?
      We survived before without ’em.
      Just modern conveniences, to make life simpler.

      Life in general, isn’t/hasn’t been simple, but for those to constantly wish it were.

      I don’t need a faraday for bullets, beans, band aids and a water filter.

      Just sayin.

      1. I’ve wrapped my dentist, doctor, surgeon, veterinarian and all their equipment,
        my house, 4×4, chainsaw, genny, rabbits foot, 4 leaf clover in foil, lined with cardboard. Shoved them all in a can.

        I’m good.

        Will add a (sarc).

      2. Joe c,

        Can’t say I disagree with that…nothing I would be stashing in a Faraday can even existed when I was a kid……but they would sure make life easier….at least in the short run until we settled back into a simple, more labor intensive lifestyle……….

        Life wasn’t so forgiving back then. Lazy folks had a rough life….I suspect we have devolved into a populace heavy with lazy folks…..they won’t fare well should a truly widespread EMP event occur….hopefully we won’t find out….besides…it appears we are doing a fine job of destroying ourselves without an EMP…..the whole world is shaking it’s collective heads as they watch……..

        1. Dennis & all.
          Sorry just a bad day.
          I know Ken means well by this post, but really, does it matter?
          If a person doesn’t have the basics, those protected gadgets won’t pull them through…. anything.

          What’s that saying?
          Those with the biggest toys win.

          Not true,
          if a true, dutiful survivor…

          ‘Nuff babbling on my side.


        2. Joe c,

          No need to apologize. I would be lying if I said I haven’t contemplated turning of the internet, the TV, the radios, etc….shut out the world, kick back and live the rest of my life in ignorant bliss of what the rest of the world is doing….let whatever happens be a surprise…….

          …….but then, I’ve got too many others I feel an obligation to protect and provide for…….

  8. Just to be on the safe side I have wrapped everything in my 33 gal trash can individually wrapped in tin foil with a cardboard liner for the can and lid. I have considered wrapping spare solar panels in either fine metal mesh or tin foil but haven’t gotten around to it yet. I check everything every 6-9 months for leakage and recharge some items. Batteries where possible are kept outside the can or wrapped in tinfoil. I keep a wind up multi band radio wrapped in tin foil in the vehicle just in case.
    in verterás of various sizes, solar panel stuff, multi meters are all good choices along with an old lap top that runs XP. Probably no internet so I don’t worry about viruses with the old operating system lol! I also have backups of manuals etc on DVDs and thumb drives just in case.

  9. Would your washer and dryer if they had grounded plugs act as faraday cages? I am closer to them than a metal trash can.

  10. In addition to EMP protection, a strong mettle can provides some physical protection as well as some water protection (rain, burst pipe, etc).

  11. I use a 55 gallon drum with a removable lid and latching ring. Wire brushed the rim of the barrel and the corresponding area of the lid and lined that area with copper tape. The inside is lined with corrugated cardboard and the whole thing is stored in my basement. When the lid is tapped down and locking ring lever is tight I think it is a reasonable Faraday cage with a lot of storage area. Among other things I store two way radios, lights, digital multi meters, laptops and so on.

    One note the copper tape has conductive adhesive that I have checked from low to high impedance. The adhesive the aluminum duct tape others have mentioned may or may not be conductive. This is a critical part of getting a good seal on the cage and a non conductive tape may do little to help seal against the nearly infinite high frequecy that is an EMP so check it out.

  12. Beyond my normal cage I keep a small radio and flashlight wrapped in foil inside an EMP bag in my GHB in the truck. At least as I am walking back home I could pick up a signal to find out what caused all the problems.

  13. I did a little experiment concerning this topic.
    I used a cell phone, an Am/Fm radio and a walkie-talkie as they operate with different radio frequencies.
    I used a metal can (galvanized) with a tight fitting lid with card board inside, an empty freezer with card board and an old microwave (unplugged).
    This is what I found:

    The cell + metal can= Phone calls, text and internet signals go through.
    The Am/Fm radio + metal can= radio worked.
    The W/T + metal can = W/T worked

    The cell + freezer= phone calls, texts and internet signals go through.
    The radio + freezer = radio worked.
    The W/T + freezer = W/T worked.

    The cell + microwave = phone calls, text and internet signals did not go through.
    The radio + microwave = radio did not work.
    The W/T + microwave = W/T did not work.

    Conclusion: The microwave blocked the cell phone, text, internet, Am/Fm radio and W/T radio (frequencies) waves (and microwaves). I believe that it would also block Electro-Magnetic Pulse (frequencies) waves.

    Can anyone else confirm these findings?

    1. I’m not sure, no one is. Most say a microwave is a good faraday. Others dispute this. ??????

    2. @Jabba,
      To specifically address the microwave oven as a Faraday cage:

      The microwave oven is designed to “keep in” (which also “keeps out”) a frequency of 2.45 Ghz. That wavelength happens to be 4.82 inches. The tiny holes in the glass door screen are small enough to “keep in” that frequency to a safe extent.

      FYI, cell phones operate on several frequencies. Mostly 800 Mhz / 1900 Mhz (1.9 Ghz). Some are 2.1 Ghz. This gives you a clue why cell phones might not work if tested in a Microwave oven for Faraday purposes. Because their operational frequency is close to the Microwave frequency attenuation characteristics.

      However this is a false sense of security with regards to EMP Faraday. Why? Because EMP is broadband. It’s a different beast.

      An EMP is a broadband, high-intensity, short-duration burst / pulse of electromagnetic energy.

      In the case of a nuclear detonation, the electromagnetic pulse consists of a continuous frequency spectrum. The EMP is a pulse (as opposed to ongoing waves). The pulse is broken down into three segments. E1, E2, E3. E1 is the bad one. It rises to maximum intensity in about 1 nanosecond. Then decays. The first approximate 5 nanoseconds is when the damage is done, so to speak.

      Here’s an attempt to provide some sort of reference:

      If it were a “wave” / wavelength which had a period of 1 nanosecond (period of one cycle), that would calculate to a frequency of 1 Ghz. (Although this is a pulse, not really a wave with a repeating period…)

      A wavelength of 100 Mhz calculates to a period of 5 nanoseconds (for example).

      Think of the damaging portion of the EMP (E1 pulse) to be broadband within (and beyond each end to an extent) this general range. This signal pulse, in theory, “could” potentially cause (via physics, the Compton Effect…) an approximate (worst case) 50,000 volt per meter “zap”. Depending on gamma and other factors…

      Long story short, a Microwave Oven may provide “some” EMP protection (if used as such) but it’s only good around 2.4 Ghz.

      Ideally, a Faraday cage for EMP would be solid conductive outer shell containment (rather than holes). It’s all about dB attenuation of that broadband pulse. It gets into design thereof, which is beyond the scope of my reply.

      Hope this helps a little.

      1. Ken,
        Makes sense…
        So, a microwave in a galvenized can isn’t a bad idea then.. I love this crowd!

    3. The microwave has an electrical cord and a fan opening. The shield container must be totally sealed due to the extreme energy of the pulse.

      1. Paleo,
        Agreed on the openings. The micro is constructed of metal. The door is designed to NOT allow leakage. Makes for a decent starting point for things ya must access from time to time. A little ingenuity could close the openings and improve (see Ken’s comment) the mesh in the door. Who knows? Might indeed, offer some level of protection.

        Someone asked about a clothes dryer, same issues. It could work, with a little effort. Most things that would fit in a microwave, will fit into a popcorn tin. Quicker, easier, maybe.

        I like Cid’s idea of nesting. This would include faraday cages stored within metal buildings. Every little bit helps, well maybe. ????????

        1. Most definitely. An EMP’s effects are not fairly distributed, all sorts of variables apply, such as distance, environment, and the very nature of the particular make and model of the equipment to be shielded.

  14. As if it matters, 50cal can in basement and large steel box.
    3 low amp solar charge controllers
    1 multi meter
    1 am/fm/weather channel radio
    an older digital watch with a current battery – canary in a coal mine kind of thing.
    2 or 3 low wattage inverters- currently one is loaned out.
    several led flashlights 18650
    2 18650 chargers that work off 110v or 12v / multiple li-ion 18650 batteries outside can.
    small 6v usb solar charger.
    old smart phone with many audiobooks in it.
    a few 12v led dimmer switches + multiple small items.
    In the big metal box**
    2 win97 laptops, battery’s have died they need 110v AC to function+ power supplies
    Two s/w radio’s another solar charger
    another multi meter
    2 40ch cb hand held
    a car mount cb 40ch
    it’s been a while, need to look again.

    I think I’d be ecstatic if the power went out long term, we heat with wood anyway.
    I’d have to check everything wondering what “might” still work(if emp) and see what I could possibly bring back to life.
    I should revisit things and add more to the stored items, it is lacking.
    forgot about the 15+ small led lights
    I’m counting on small led lights working after emp but most are stored anyway.

  15. Recently found:
    Lafayette Telsat SSB-75 in my stuff, I have no idea where I picked it up or if it works.No acceptable antenna to try it out.

    1. Since the light source in an LED light is a diode, the diode itself is vulnerable to the current overload, as the modulating circuit is easily by-passed by the spike, allowing over current to damage the LED.

    2. The Rule of Thumb, when dealing with an EMP, is this:

      Old is Good. New is Bad.

      Old fashioned flashlights with bulbs. Coleman gas lights. Oil/Kerosene Lamps. Candles. Cars without electronic ignitions, or electronically controlled fuel injectors. Better they have a mechanical fuel pump and a carb.

      If a new technology device still works after an EMP, it will be because of variables in its favor, and simple luck. But, each new EMP will reshuffle the deck, so equipment which survived one EMP, may not survive another.

      In any case, when it gets hot enough for idiots to fire off their EMP weapons, it shall be hot enough to spell the end of Humanity. Let us hope they EMP only the Western Half of the U.S. and not the EASTERN half…with all its Nuclear Reactors.

  16. One thought on the LED (light emitting diode) flashlights. It they’re exposed, they’re fried. Don’t forget the old style automotive tail light bulbs, 1157 and close. I have several “reverse light” bulbs. Could be used for light 12vdc. One out building is wired with several of these sockets and bulbs. Just need to attach battery. Thought about updating to LED, but didn’t due to potential emp. The old style sure draws a lot more power, oh well.

    1. Very good idea of using 12v automotive, non-led, light bulbs for illumination fixtures!

    2. Plainsmedic:

      If I remember correctly, 1157 was the dual-filament tail/brake combo. By using a simple SPDT switch, you can have a High-Low setting, as well as a backup filament if the first one burns out.

      1. tmcgyver,
        Yes, the 1157 is dual filament. I can’t recall the brighter reverse light bulb, 1156 or 1158? I’d have to dig ’em out. Anyway, you guys all get this. I got all my sockets from an old salvage yard. They have really changed salvage yards, from the old days.

    3. Plainsmedic , you reminded me of a story from a father and son from Canada. There was along term power outage from a storm. Everyone in their apt.building only had electric heat. It got so cold in the apts that butter stayed frozen on the table.
      The son grabbed his car battery and a head light from their car. They used the heat from the light to soften the butter so they could spread it on bread they had thawed under the light.
      You could make reflective pans for them too that would hold the socket and reflect and concentrate the light.
      Definitely thinking out side of the box…

  17. Greetings, Ken and all, my first posting, long time lurker.

    I have come across what I believe to be an adequate Faraday Shield which I use for USB thumb drives and SD cards. It is a metal container for kitchen size matches sourced from the camping section. I will follow up with a link in a subsequent posting so that it may be moderated.

    On a similar note have y’all seen a Raspberry Pi? It is a full-blown computer that fits in the top pocket of my shirt. Of course, it requires a mouse and keyboard of the USB sort along with a monitor. The Pi does not run on Windows(R) but on Linux instead, which is a huge plus, saving you the Microsoft(R) Tax.

    If you only use a computer for the average web browsing, e-mail,word processing or spreadsheet functions then the Linux is completely transparent to the user and you will not have to learn a new Operating System.

    I have used my Raspberry Pi most of this year for all of my computer needs since my laptop died.

    I do not think that this is off-topic since such a small complete computer would save a lot of space in the metal trash can that I keep things in.

    Forgetful John

    1. Forgetful John,
      Sounds like a good idea. Glad to see ya post. More input the better.
      Would be interested to hear more about the pocket computer…

      1. BJH,

        The Raspberry Pi 4 is a small quad-core 64-bit, up to 8 Gig Ram computer that originally came out to teach programming and such. There is a lot of information out on the interweb if you would search a bit.

        I can only tell you my experience which is that my laptop was getting long in the tooth so I took a gamble to save some bucks. I spent a little over a hundred for a complete Canakit. This includes a case and cables along with a power supply. Just the computer board itself is around 35 or so! I was able to save around 200 versus a replacement laptop.

        The Operating System, Raspbian, is a derivative of Debian Linux which resides on a micro-SD card and all my other data I keep on a USB thumb drive. If it was to die then I would just get another board. Just think, 35 will get you a complete replacement slightly bigger than a pack of smokes for your garbage can.

        Also, from a privacy stand point, If I was to remove my USB data drive and the micro-SD card there is nothing left on the computer. I bet Hunter wishes he could have done that, hyuck hyuck.

        I have been running this thing as a replacement for my home computer for the last 9 months.

        Forgetful John

  18. I nest my electronics and such in two or more Faraday bags. You can get them for a fairly good price if you buy in bulk.

  19. question to all,
    do rechargeable batteries like the eneloops need to be EMP protected ? i know the chargers do but what about the batteries themselves ?
    we have had 2 CME events in as many weeks. i need to check my stuff today. CME and EMP events are my biggest fear, it wouldn’t be local like local weather event where other parts of the country would come to help. it would put EVERYONE into the dark ages, literally.
    thanks in advance

  20. NYScout,
    I think batteries are safe from EMP. Only ones that might be affected would be ones in a charger at the time of an emp. Might want to store extras with you electronic gear in your Faraday cage. Where you get into trouble is electronic equipment with long cords, which act as antennas and absorb the EM pulses.

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